Although whistles have been in existence for quite some time there tend to be disadvantages associated with various designs and it is believed that there is an ever increasing need for high quality whistles which can be produced relatively cheaply, the main usage of these whistles being by referees. Such whistles will usually be of a well known shape which may be referred to as a flat-topped "mandolin" shape in side elevation. A well known disadvantage associated with some types of pea whistles is that loss of sound can occur by "overblowing" or by sticking of the freely moving pea in the whistle. Thus, attempts have been made to generally reproduce the loud piercing sound required without incurring the disadvantages of such pea-type whistles.
Even so, it is the Applicant's belief that their own pea-type whistles in particular do not suffer from this disadvantage but, partly in view of the unfavourable reputation of whistles which do tend to have this disadvantage, the fashion and popular trend for whistles seems to be currently favouring pea-less whistles.
Additionally a pealess whistle may also have the advantage that a higher frequency can be generated than can generally be achieved with a pea-type whistle. Since higher frequency sounds are more easily distinguished from background noise, referees in particular generally prefer a whistle yielding as high a pitched sound as possible. Additionally, pealess whistles generally avoid the need for expensive assembly and test procedures that are required with pea-type whistles.
One design of pealess whistle is shown in U.S. Pat. Specification No. 4,821,670 (Foxcroft et al) but it is believed that this proposed whistle design still tends to have certain disadvantages, some of which are detailed as follows:
1. Air blown into the whistle shown in 4,821,670 exhausts through the top and side surfaces and, as such, there is a possibility that the sound chambers may become blocked by fingers gripping onto the sides of the whistle overlapping the side exhaust vents. Indeed, other pealess whistles have been designed which exhaust through the side of the whistle and even also underneath the whistle directing the sound directly into the hand of the user, thereby reducing the maximum sound the whistle could otherwise be designed to release. In practice, it is believed that the provision of side venting of the exhaust air tends to provide a significant disadvantage. PA1 2. The whistle shown in 4,821,670 has a central whistle chamber element of greater length than two other whistle chamber elements provided on either side of the central whistle chamber element and, in order to cater for the extra long central whistle chamber element required, an extension or boss is needed which juts out from the general "mandolin" shape in a manner which it is believed detracts from the overall appearance of the whistle and is generally inconvenient overall in the manufacturing process and may well unnecessarily increase the costs of production. PA1 3. It is believed that the form and disposition of the whistle elements shown in 4,821,670 are unnecessarily complex, such complexity apparently being believed necessary in order to produce complex harmonics and beats that increase the piercing quality and audibility of the sound. PA1 4. The whistle is made as a three-part moulding and the Applicant believes that the moulding process can be made much simpler. PA1 5. Owing to the size and disposition of the whistle chamber elements it is believed that the overall shape of the whistle is more bulky than need be the case in order to achieve the same or a similar quality of sound considered sufficient for the intended use.